PubMed · 819826
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
K E Papa. Linkage groups in Aspergillus flavus.. https://pubmed.ncbi.nlm.nih.gov/819826/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Aspergillus flavus is a ubiquitous fungus commonly found in a variety of ecological niches including soil, crops, the air, and humans. In humans, it is the second leading cause of invasive aspergillosis (IA) and is linked to other illnesses through contamination of agricultural products with aflatoxins. As such, A. flavus threatens food safety, economic wellbeing, and human health, particularly in less developed regions and countries such as Cameroon. To mitigate these effects, farmers and clinicians rely on triazoles to reduce aflatoxin contamination and treat IA. However, a consequence of increasing triazole use is the emergence and spread of triazole resistance in both agriculture and clinics. To identify the prevalence of triazole resistance and the potential genetic relationships among triazole resistant and susceptible strains, this study investigated antifungal susceptibility to both clinical and agricultural triazoles and analyzed genetic variation among various ecological niche populations of A. flavus in Cameroon. Strain genotypes were obtained through analysis of six polymorphic microsatellite markers. Our analyses revealed that 30.3% (17/56) of the strains were resistant to at least one of the four triazoles, with increased minimum inhibitory concentrations found among crop-isolated strains. A Permutational Multivariate Analysis of Variance suggested limited ecological niche-based clustering of genotypes, consistent with frequent gene flow and dispersal among ecological niches. A multilocus linkage disequilibrium analysis revealed evidence of non-random recombination in A. flavus. Overall, this study elucidates the interplay between ecological pressures, antifungal resistance, and genetic differentiation, and invites alternative methods to control aflatoxin contamination in foods without the use of agricultural fungicides.
Genetic exchange by asexual filamentous fungi is presumed to be limited to isolates in the same vegetative compatibility group (VCG). To evaluate genetic isolation of Aspergillus flavus due to vegetative incompatibility, three gene regions were chosen that contained closely spaced nucleotides that were polymorphic among some of the six VCGs examined. A member of each VCG was collected from five regions across the southern United States. Isolates belonging to the same VCG had similar sets of single nucleotide polymorphisms regardless of isolate origin. The six VCGs formed four genetically distinct groups. Although recombination between certain pairs of VCGs could not be excluded, none was found for YV36, the VCG that includes the atoxigenic A. flavus isolate currently used to mitigate aflatoxin contamination in cotton in Arizona.
Preparation of 98% ee (R)-4-chloro-2-butanol was carried out by the enzymatic hydrolysis of chlorohydrin esters, using fungal resting cells and commercial enzymes. Hydrolyzes were carried out using lipases from Candida antarctica (Novozym 435), C. rugosa, Rhizomucor miehei (Lipozyme IM), Burkolia cepacia, and resting cells of Rhizopus oryzae and Aspergillus flavus. The influence of the enzyme, the solvent, the temperature, and the alkyl chain length on the selectivity of hydrolyzes of isomeric mixtures of chlorohydrin esters is described. Regioselectivity was higher than 95% for some of the tested lipases. Novozym 435 allowed preparation of the (R)-4-chloro-2-butanol after 15 min of reaction at 30-40 degrees C.